Abstract
Comparative genomics analyses empowered by the wealth of sequenced genomes have revealed numerous instances of horizontal DNA transfers between distantly related species. In eukaryotes, repetitive DNA sequences known as transposable elements (TEs) are especially prone to move across species boundaries. Such horizontal transposon transfers, or HTTs, are relatively common within major eukaryotic kingdoms, including animals, plants and fungi, while rarely occurring across these kingdoms. Here, we describe the first case of HTT from animals to plants, involving TEs known as Penelope- like elements, or PLEs, a group of retrotransposons closely related to eukaryotic telomerases. Using a combination of in situ hybridizations on chromosomes, PCR experiments and computational analyses we show that the predominant PLE lineage, EN(+)PLEs, is highly diversified in loblolly pine and other conifers, but appears to be absent in other gymnosperms. Phylogenetic analyses of both protein and DNA sequences reveal that conifers EN(+)PLEs, or Dryads, form a monophyletic group clustering within a clade of primarily arthropod elements. Additionally, no EN(+)PLEs were detected in 1,928 genome assemblies from 1,029 non-metazoan and non-conifer genomes from fourteen major eukaryotic lineages. These findings indicate that Dryads emerged following an ancient horizontal transfer of EN(+)PLEs from arthropods to a common ancestor of conifers ~340 million years ago. This represents one of the oldest known interspecific transmissions of transposable elements, and the most conspicuous case of DNA transfer between animals and plants.
Keywords
lateral transmission,
transposable elements,
Dryads,
loblolly pine
Citation
Lin, Xuan; Faridi, Nurul; Casola, Claudio. 2016. An ancient trans-kingdom horizontal transfer of
Penelope -like retroelements from arthropods to conifers . Genome Biology and Evolution: evw076-. 46 p. 10.1093/gbe/evw076
